Snap-action electric switch



May 25, 1965 w. D. WILSON SNAP-ACTION ELECTRIC SWITCH Filed March 22,1963 3 Sheets-Sheet l INVENTOR. 144214D Mzsv ATTORNEX May 25, 1965 w. 0.WILSON SNAP-ACTION ELECTRIC SWITCH 3 Sheets-Sheet 2 Filed larch 22, 1963w PM w 8 \1 6 4% M 6 w w w w Z Z M a a a 4M 9%. Z I 5 V w m I an d m w.4 M M 2 w M 6 w w Ma ///////7 ATTORNEY.

May 25, 1965 w; D. WILSON SNAP-ACTION ELECTRIC SWITCH 3 Sheets-Sheet 25Filed March 22, 1963 INVENTOR. 114414465 D. M490 A TTORNEY.

United States Patent 3,185,786 SNAP-ACTION ELECTRIC SWITCH Wallace D.Wilson, Middletown, N.J., assignor to Elastic Stop Nut Corporation ofAmerica, Union, N.J., a corporation of New Jersey Filed Mar. 22, 1963,Ser. No. 267,088 3 Claims. (Cl. ZOO-67) This invention relates generallyto the art of switches, and more particularly to improved over-centerswitches of the type usually employed in combination with time delaycontrol apparatus. The improved over-center switches of the presentinvention are particularly useful for opening or closing electricalcircuits after a lapse of a predetermined time interval following theactuation of the time delay control apparatus by an operator.

It has been proposed to employ over-center type switches with time delaycontrol apparatus. In substantially all of the prior art switches ofthis type, the switching lever member that is responsible for theswitching action is securely fixed adjacent to one of its ends to a baseor block member. Thus, to initiate a desired switching action, one mustapply to the switching lever member a force of sufficient amplitude tobend it and to actuate, in turn, a contact assembly. While such priorart switches are suitable for certain applications, they leave somethingto be desired when the operating force that is transmitted to theswitching lever member is limited and when very precise switching isrequired. It is an object of the present invention to provide improvedover-center switches that may be actuated with relatively less forcethan corresponding prior art overcenter switches.

It is another object of the present invention to provide improvedover-center switches having adjustable means for limiting the travel ofa lever member so as to assure faster and more effortless switching.

A further object of the present invention is to provide improvedover-center switches wherein the lever member is pivotably attached toadjacent parts for reducing the operating force required to actuate theswitches.

Still a further object of the present invention is to provide improvedover-center switches of the type described that are relatively simple inoperation and construction, easy to manufacture, and highly efiicient inuse.

These and other objects of the present invention are achieved in anover-center switch comprising a lever memher, and over-center springmeans arranged in a manner to spring load the lever member for rotationin a plane over a limited distance about one of its ends, the latter endbeing pivotally mounted upon the base of the switch and functioning as afulcrum for the lever member. One end of the over-center spring means isalso pivotally mounted on the base, and its other end is pivotallyengaged with the non-fulcrum end of the lever member in a manner wherebythe lever member compresses the over-center spring means so as to biasthe lever member in either of two opposite directions from a position ofdead center. Thus, the lever member is biased for movement, with snapaction, in the aforementioned two opposite directions from the positionof the lever member when it compresses the over-center spring means amaximum. Motion transmitting means, usually from, and controlled by,time delay control apparatus are cooperatively coupled to the levermember to urge it in either of the two opposite directions. Adjustablestop means are provided to limit the distance travelled by thenon-fulcrum end of the lever member in at least one direction, therebyincreasing the sensitivity of the switch. Contact assembly means arecooperatively coupled to the lever member and are adapted to be actuatedby the movement of the lever member.

The novel features of the present invention, as well as 3,185,786Patented May 25, 1965 the invention itself, both as to its organizationand method of operation, will be understood in detail from the following description when considered in connection with the accompanyingdrawings in which similar reference characters rfeer to similar partsthroughout, and in which:

FIG. 1 is a fragmentary longitudinal section through a time delaycontrol apparatus and over-center switch illustrating the switch in oneoperative position in accordance with the present invention;

FIG. 2 is a cross-sectional view of the switch taken along the line 22in FIG. 1;

FIG. 3 is a cross-sectional view of the switch, taken along the line 3-3in FIG. 2, in one operative position thereof in accordance with thepresent invention;

FIG. 3a is a cross-sectional view of the switch, taken along the line3a--3a in FIG. 2, in said one operative position thereof;

FIG. 4 is a view similar to FIG. 3, but illustrating the switch inanother operative position thereof in accordance with the presentinvention;

FIG. 4a is a view similar to FIG. 3a, showing the switch in said anotheroperative position thereof;

FIG. 5 is an exploded view of some parts of the switch to illustratetheir pivotal mountings in accordance with the present invention;

FIG. 6 is a plan view of another embodiment of an over-center switch inaccordance with the present invention;

FIG. 7 is a cross-sectional view of the switch shown in FIG. 6, takenalong the line 7-7, and showing the switch in one operative positionthereof;

FIG. 8 is a cross-sectional view of the switch shown in FIG. 6, takenalong the line 8-8; and

FIG. 9 is a cross-sectional view similar to FIG. 7, but showing theswitch in another operative position thereof.

Referring, now, particularly to FIG. 1 of the drawing, there is shown anover-center switch 10 cooperatively associated with time delay controlapparatus 12 for actuating the switch 10 by means of a rod14, the latterbeing mounted for reciprocatory motion in a solenoid 16. The rod 14 isadapted to be reciprocated in the directions in dicated by the doubleheaded arrow 18 by the time delay control apparatus 12 in a mannerdescribed in US. Patent No. 2,489,381, issued on November 29, 1949, toC. Lindahl for Time Delay Control Apparatus. The time delay apparatus 12may also be of the type described in US. Patent No. 2,855,481, issued onOctober 7, 1958 to C. Lindahl for Time Delay Apparatus. Since thetimedelay control apparatus 12 does not form a part of the presentinvention other than to supply a reciprocatory force to a lever member20 for operating the switch 10, it will not be described herein,reference being made to the aforementioned patents for details of itsoperation.

The lower end of the rod 14 is of reduced diameter and has slidablymounted thereon a lost motion element in the form of a sleeve 22, thetravel of which relative to the rod 14 is limited in the lower directionby :a riut 24, and in the upper direction by adjustable lock nuts 26 and28 threaded on the rod 14. The lower end of the sleeve 22 is recessed toreceive a spring 30 which acts to bias the sleeve 22 away'from the nut24 and towards the lock nut 28. The outer surface of the sleeve 22 ischanneled to provide end shoulders or oollans 32 and 34.

The sleeve 22 is disposed within an opening 36 in the lever member 20 sothat the lever 20 may be rotated downwardly or upwardly about itsfulcrum end 38 by the shoulders 34 and 32, respectively, when the rod 14is reciprocated. The spring 30 acts in the nature of a booster springwhich in eifec-t moves the lever member 20 across a dead center positionfrom a position ahead of that at which the switch would be caused topass its dead center position in the absence of the lost motionconnection and booster spring 3%, in a manner to be explainedhereinafter.

Referring, now, to FIGS. 2, 3, 3a, 4, 4a, and 5 the switch is showncomprising a base of insulating material adapted to be secured to thetime delay control apparatus 12 by any suitable means, as by screws (notshown) engageable in threaded openings 42, 44, 46 and 48. The rod 14extends through an elongated opening 50 in the base 40. Means areprovided to mount the lever member 20 pivotally on the base 40. To thisend, a block 52 of insulating material is fixed to the base 40 by screws54 and 56 adjacent to an edge 58 of the base 40. The block 52 is formedwith a V-groove 59 into which the fulcrum end 38 of the lever member 20is pivoted. It will now be understood that the lever member 20 isadapted to rotate about its fulcrum end 38 so that its non-fulcrum end60 describes an arc of rotation in a plane perpendicular to the base 40.The lever member 20 is preferably of spring steel.

Means are pnovided to spring load the lever member 20 and to cause it tomove in opposite directions, with snap action, from a dead cent-erposition. To this end, over-center spring means 62 are provided with arod 64 having an enlarged head 66, the latter being formed with aV-g-r-oove 68. A knife edge '70, supported by a block '72 that isanchored to the base 40 by a screw 74, is positioned to pivotally engagethe groove 68 in the head 66. The rod 64 is disposed loosely within .ahelical spring 76, the spring 76 being contained with a hollow cylinder78. The outside end of the cylinder '78 is formed with a V-groove 80adapted to engage pivotally the non-fulcrum end 60 of the lever member20. The block '72 is disposed opposite the block 52 and spaced from it adistance so that the spring 76 is compressed a maximum when the levermember 20 and the over-center spring means 62 are in position ofsubstantially linear alignment, that is, in a position of dead center.Because of the spring loading provided primarily by the spring '76 ofthe over-center spring means 62, the lever member 20 may move upwardlyor downwardly from the position of dead center with a snap action.

The lever member 20 has a winged member 82 of insulating material fixedto it adjacent to its non-fulcrum end 60, as shown in FIG. 5. The wingedmember 82 is formed with wings 84 and 86 extending in substantiallyopposite directions in the general plane defined by the lever member 20and comprise means to move movable contact arms 88 and 90, the latterbeing provided with movable contacts 92 and 94, respectively.

The contact arms 88 and are anchored to the base 40 by screws 96 and 98respectively. The screws 96 and 98 also engage cont-act strips 100 and102 provided with screws 104 and 106, respectively, for makingelectrical connections with the contacts 92 and 94, respectively.

A pair of upper fixed contacts 108 and 110 are adapted to be engaged bythe movable contacts 92 and 94, respectively, when the non-fulcrum end60 of the lever member 20 is moved upwardly. The contacts 108 and 110are fixed to the base 40 by resilient contact members 112 and 114 and byscrews 116 and 118, respectively. Thus, electrical connections can bemade to the fixed contacts 108 and 110 through the screws 116 and 118,respec tively.

When the lever member 20 is in its downward position, as illustrated inFIGS. 3 and 3a, the movable contacts 92 and 94 are adapted to be urgedby their resilient arms 88 and 90 against lower fixed contacts 120 and122 respectively. The fixed contacts 120 and 122 are fixed to the base40 by resilient straps 124 and 126 and screws 128 and 130 (FIG. 2)respectively. Electrical c0nnections may be made to the lower fixedcontacts 120 and 122 by means of screws 128 and 130 respectively.

The terminal position below dead center that the lever member 20 maymove is determined by stop means cond sisting of a set screw 132threaded through the base 40 and contacting the winged member 82. Thesensitivity of the switch 10 can be adjusted by raising or lowering thescrew 132 so that the amount of force necessary to rotate the levermember 20 upwardly past its dead center position is a desired magnitude.Thus, the screw 132 may be adjusted so that the lever member 20 is justbelow its dead center position, and the amount of force necessary tomove it past its dead center position is essentially a minimum. Theupper limit of travel of the lever member 20 is determined by thecontact assemly including the movable contacts 92 and 94 and the upperfixed cont-acts 108 and 110, respectively. If desired, however, stopmeans (not shown) similar to the screw 132 may be positioned adjacent tothe upper side of the lever member 20 for limiting its upper terminalposition.

In ope-ration the time delay apparatus 12 is actuated by an operator andthe lever member 20 is rotated downwardly about its fulcrum end 38 bythe downward movement of the rod 14 in the time delay control apparatus12, the upper collar 34- :of the sleeve 22 engaging the upper surface ofthe lever member 28 and rotating it downwardly past the dead centerprovided for by the over-center spring means 62. The lever member 20then snaps to its lowest terminal position determined by the position ofthe adjustable screw 132. After a predetermined time, usuallyadjustable, controlled by the apparatus 12 the rod 14 begins to moveupwardly causing the lower collar 32 of the sleeve 22 to engage thelower surface of the lever member 20 and rotates the latter upwardlypast the dead center position of the over-center spring means 62. Duringthe upward movement of the lever member 20 the spring 30 of the lostmotion sleeve 22 is compressed thereby boosting the lever member acrossits dead center position with an additional force provided by thecompression of the spring 30.

Referring, now, to FIGS. 6, 7, 8 and 9 there is shown another embodiment10a of an over-center switch of the present invention. The switch 10acomprises a base of insulating material. A lever member 142 of springsteel has a fulcrum end 144 mounted within a groove 146 in a block 148fixed to the base 140. A U-shaped over-center spring means 150 is formedwith a notched end 152 that is pivotally mounted for rotation about aknife edge 154. The knife edge 154 is fixed to the base 140 by means ofa screw 156. A notched end 158, oppo site to the notched end 156, of theover-center spring means 150 is pivotally engaged with the non-fulcrumend of the lever member 142 in a manner whereby the lever member 142 isspring loaded so that it can rotate about its fulcrum end 144 upwardlyor downwardly, with snap action, past a dead center position. The rod 14of the time delay control apparatus 12 is disposed within a slot 162 inthe lever member 142 and the opposite shoulders 34 and 32 of the sleeve22 are adapted to rotate the lever member 142 downwardly or upwardly inthe same manner explained for the operation of the switch 10. The rod 14extends through a hole 164 in the base 140.

A pair of movable contacts 166 and 168 is fixed adjacent to one of theends of a pair of resilient arms 170 and 172, the other ends beinganchored to the base 140 by screws 174 and 176 respectively. The arms1'70 and 172 are adapted to be moved upwardly by the wings 178 and 180of a winged member 182 respectively. A pair of upper fixed contacts 184and 186 is fixed to the base 140 by resilient arms 188 and 190 by screws192 and 194, respectively, as shown in FIG. 8. A pair of lower fixedcontacts 196 and 198 is fixed to the base 140 in a position whereby theywill be contacted by the movable contacts 166 and 168, respectively,when the lever member 142 is rotated downwardly.

A set screw 200 is threaded through the base 140 and adapted to engagethe lower surface of the winged member 182 limiting the lower terminalposition of rotation of the lever member 142. It will be understood thatthe screw 200 may be raised or lowered to position the lever member 142below its dead center position so that a desired magnitude of force maybe used to move the lever member 142 upwardly past its dead centerposition. The upper terminal limit of the lever member 14-2 may bedetermined by an adjustable screw (not shown) similar to the screw 2% orit may be determined by the contact assembly comprising movable contacts166 and 163 and the fixed contacts 184 and 186 respectively.

The operation of the switch a is similar to that described for theswitch 10. Motion of the rod 14, controlled by the time delay controlapparatus ,12 initially moves the lever member 14 in one direction. Forexample, let it be assumed that the lever member 142 is initiallyrotated downwardly about its fulcrum end 144. The lost motion sleeve 22will cause the lever member 142 to move downwardly past its dead centerposition until the winged member 182 engages the screw 200. After apredetermined time delay, controlled by the time control apparatus, theshoulder 32 of the sleeve 22 will urge the lever member 142 upwardlyabout its fulcrum end 144. Once past its dead center, the U-shapedover-center spring means 150 will cause the lever member 142 to moveupwardly with a snap action until the movable contacts 166 and 168engage the upper fixed contacts 184 and 186, respectively.

From the foregoing description there has been described over-centerswitches of the type wherein a lever member is connected pivotally atopposite ends thereof. Overcenter spring means are also connectedpivotally at opposite ends thereof in a manner to spring load the levermember so that the resistance offered by the lever member in passingthrough a dead center position is reduced. Adjustable stop means havealso been described for increasing further the sensitivity of the switchoperation. Since various modifications of the present invention may bemade without departing from the spirit and scope thereof, it is desiredthat the foregoing description shall be considered merely asillustrative and not in a limiting sense.

I claim:

1. In a switch of the type wherein a fixed contact is adapted to beengaged by a movable contact, and wherein said movable contact is movedby means including a spring loaded lever member, the improvementcomprising, in combination,

(a) a base,

(b) said lever member having two opposite ends,

(0) means pivotally mounting one of said ends of said lever member onsaid base,

(d) over-center spring means having two opposite ends,

(e) means pivotally mounting one of said ends of said over-center springmeans on said base, the other ends of said lever member and saidover-center spring means pivotally engaging each other and compressingsaid over-center spring means to bias said lever member in either of twoopposite directions from a dead center position,

(f) motion transmitting means engaging said lever member to urge it ineither of said two opposite directions, and

(g) adjustable means disposed to engage and limit the movement of saidlever member in one of said two opposite directions.

2. In a switch of the type wherein a fixed contact is adapted to beengaged by a movable contact, and wherein said movable contact is movedby means including a spring loaded lever member, the improvementcomprising in combination,

(a) a base,

(b) said lever member having two opposite ends,

(0) means pivotally mounting one of said ends of said lever member onsaid base,

(d) over-center spring means having two opposite ends,

(2) means pivotally mounting one of said ends of said over-center springmeans on said base, the other ends of said lever member and saidover-center spring means pivotally engaging each other and compressingsaid over-center spring means to bias said lever member in either of twoopposite directions from a dead center position,

(f) motion transmitting means engaging said lever member to urge it ineither of said two opposite directions, and

(g) adjustable screw means threaded in said base and disposed to limitthe movement of said lever member in one of said two oppositedirections.

3. An over-center switch for use with time delay control apparatushaving a motion transmitting member adapted to move in either of twoopposite directions, said switch comprising,

(a) a base of insulating material,

(b) a lever member having two opposite ends,

(0) over-center spring means having two opposite ends,

(d) means pivotally mounting one of said ends of said lever member tosaid base for rotation thereabout in a plane,

(e) means pivotally mounting one end of said overcenter spring means tosaid base for rotation there about in said plane, the other ends of saidlever memher and said over-center spring means being in pivotalengagement with each other,

(f) said lever member compressing said over-center spring means amaximum in a position of dead center, said motion transmitting membercooperatively engaging said lever member, whereby to move said levermember in either of said two opposite direction-s from said position ofdead center,

(g) a contact assembly having means including a movable contactcooperatively engaged with said lever member for movement thereby,

(h) at least one fixed contact fixed to said base for engaging saidmovable contact, and

(i) adjustable screw means disposed in said base to limit the movementof said lever member in at least one of said two directions.

References Cited by the Examiner UNITED STATES PATENTS BERNARD A.GILHEANY, Primary Examiner. ROBERT K. SCHAEFER, Examiner.

1. IN A SWITCH OF THE TYPE WHEREIN A FIXED CONTACT IS ADAPTED TO BEENGAGED BY A MOVABLE CONTACT, AND WHEREIN SAID MOVABLE CONTACT IS MOVEDBY MEANS INCLUDING A SPRING LOADED LEVER MEMBER, THE IMPROVEMENTCOMPRISING, IN COMBINATION, (A) A BASE, (B) SAID LEVER MEMBER HAVING TWOOPPOSITE ENDS, (C) MEANS PIVOTALLY MOUNTING ONE OF SAID ENDS OF SAIDLEVER MEMBER ON SAID BASE, (D) OVER-CENTER SPRING MEANS HAVING TWOOPPOSITE ENDS, (E) MEANS PIVOTALLY MOUNTING ONE OF SAID ENDS OF SAIDOVER-CENTER SPRING MEANS ON SAID BASE, THE OTHER ENDS OF SAID LEVERMEMBER AND SAID OVER-CENTER SPRING MEANS PIVOTALLY ENGAGING EACH OTHERAND COMPRESSING SAID OVER-CENTER SPRING MEANS TO BIAS SAID LEVER MEM-